Process for the manufacture of protocatechuic aldehyde and its substitution products



Patented Dec. 13, 1932 STATES FRANZ ELGER, 0F BASEL, SWITZERLAND,ASSIGNOR TO HOFFMAN-LA ROCHE INC., 0]?

NUTLEY, NEW JERSEY, A CORPORATION OF NEW JERSEY PROCESS FOR THE.MANUFACTURE OF PROTOGATECHUIC ALDEHYDE AND ITS SUBSTITUTION PRODUCTS NoDrawing. Application filed November 19, 1931, Serial No. 576,218, and

It has been found that protocatechuic aldehyde and its products ofsubstitution may easily be obtained with a good yield by allowinghydrogenperoxide in alkaline solution to react with4-hydroxyisophthalaldehyde and its derivatives.

Through the researches of Dakin (American Chemical Journal, vol. 42,1909, page 477) it has become lmown, that by treating oandp-hydroXybenzaldehydes with hydrogenperoxide in alkaline solution 0- andp-dihydroxybenzene compounds are obtained. It was impossible to foretellwhat course this interesting reaction, that is the exchange of thealdehyde group for the hydroxy group, would take, if an aldehyde groupwere present in the orthoas well as in the para-position to the hydroxygroup. It has nowbeen found that it is surprisingly easy to exchangeonly the ortho-aldehyde group for the hydroxyl group and that thusdihydroxybenzaldehydes are obtainable in very good yield.

Example 1 15 parts of 4-hydroxyisophthalaldehyde are dissolved in 100parts by volume of normal sodium hydroxide and to this is added anequimolecular quantity of hydrogenperoxide. The solution, which at firstis yellow, soon changes its color to reddish-brown. By extraction withether the protocatechuic aldehyde is isolated from the reaction product;after recrystallization from water it melts at 150 C. The equation ofthis reaction is as follows:

CH0 CH0 1 +Hz0g= +H.OOOH

- CHO )11 0H Emample 2 18 parts of 4-hydroxy-5-methoxyisophthalaldehyde(of. J. and P. Koetschet, Helvetica Ghimica Acta, vol. 3, 1930, page482) are dissolved in 100 parts by volume of a solution of sodiumhydroxide and to this solution are added 120 parts by volume of 3%hydrogenperoxide. The yellow solution gets warm and in Germany December8, 1930.

changes its color to dark red. By treatment with ether a crude materialis obtained which 1s purified by recrystallization from benzene andtoluol. The 3-methyl-ether of the gallic aldehyde thus obtained melts at135 C. The equation of this reaction is as follows CH0 CH0 CHiO OH CHOCHO

my hand.

FRANZ ELGER.

